BULLETIN OF TIIK UNITED STATES FISH COMMISSION. 135 



is. <n THE l»IU IMIMJIM <>l TIIK TIAT1.UAKY <«l \M»N VMH.IM 



TAMAOF THE CETAfEA, 



By JOHIV A. KVDER. 



The oppdrtunity to dissect a gravid female of Phoccena communis 

 having recently presented itself through the great liberality of the 

 Director of the U. S. National Museum, Professor Baird, the dissection 

 being in part conducted by my friends Mr. J. L. Wortinan, of the Army 

 Medical Museum, and Mr. F. W. True, curator of the Department of 

 Mammals in the National Museum, I availed myself of the opportunity 

 to make an examination of the structure and condition of the mammary 

 gland of the adult, which contained a foetus in its uterus about a foot 

 loug. 



This specimen became of stdl greater interest when 1 subsequently 

 happened to be fortunate enough to obtain excellent sections of the 



KXI'I.ANATION- OF FIGURE6. 



Upper figure: Vertical section through the rudiment of the mammary gland of Globioctphalvs. en- 

 larged 200 times, ep, outer layer of epidermis ; ep', deep or Malpighian layer of the same;/, cellular mass 

 in the center of the glandular rudiment derived from the outer layer: m, mesoblast or connective tis- 

 sue. 



Lower figure; A similar section, but drawn diagramniatically through the incipient nipple p and fol.'s 

 »• r # which inclose the former, finally giving rise to the walls of the mammary fossa and growing up 

 over the nipple so as to conceal it from without at a very early stage. 



« 



first traces of the mammary gland in a very young female foetus of the 

 blackfish, Globiocephalus melas, about 2 inches long, the rudiments of 



